Tag Archives: cosmic radiation

Uncharted territory: how big is the universe?

How far is too far? On groggy Sunday mornings, the gym may seem “too far”, while for two long-distance lovers separated by circumstances, they are always “close enough”. For some, distance is relative to our motivation. Space, however, does not care what you think.

Voyager 1. Image from NASA.

It’s been over 35 years since NASA’s launch of Voyager 1, and since then, it has travelled almost 20 trillion kilometers from home. You might think that that’s far, but in the grand scheme of the universe where distances are measured with respect to light, it has travelled a mere 18 light-hours. To put that into perspective, the nearest star to our Sun, Proxima Centauri, is about 4.24 light-years away.

So how big is the universe then?

Before we address that, we need to know how old the universe is. Based on measurements of the cosmic microwave background, which is basically leftover radiation from the Big Bang, astronomers are confident that the universe is about 13.8 billion years old. Since Distance = Velocity × Time and nothing can travel faster than light (?), the universe must have a radius of 13.8 billion light-years, right? Wrong!

The Doppler effect on the pink sound waves. Image from user Charly Whisky from Wikipedia.

The short answer to the size of the universe is that it is at least 93 billion light-years in diameter. The reason that the universe is larger expected is because the universe is expanding. This can be determined by the apparent redshift of distant stars due to the Doppler Effect. So an object emitting light from 13.8 light-years away would have moved to a position much farther away.

One thing to note, is that this measurement is only what we can observe.  The observable universe from another planet billions of light-years away is likely different from our reference frame of the Earth. Is the universe infinite? Perhaps. But for now, we can appreciate that even though our paradigm of the universe is limited, there is still much to explore; we have observed billions of galaxies, and in each are billions of stars, each hosting their own worlds much like ours. Despite the uncertainty in the true size of the universe, we know that space is vast. As the Dutch artist Vincent van Gogh had once said, “for my part I know nothing with any certainty, but the sight of the stars makes me dream.”

If you have 45 minutes to spend exploring part of our Solar System, check out Alphonse Swinehart’s video below, where you travel from the Sun to Jupiter at the speed of a photon! Do yourself a favour and enjoy the video in full screen mode.

– Trevor Tsang


Possibility of Life in Mars

Mumma, Michael J. in the article “The Search for Life on Mars” states that because of considerable similarities of earth and mars, it may be possible that life exists in some forms in Mars. Although, up to now, there has been no evidence to prove the idea of existence of life in Mars, recent discoveries propose that Mars was once habitable.



Credit: Wikimedia

Scientists have conducted several investigations and researches in order to prove the possibility of life in Mars. Finding factors that are vital for the possibility of life, has been the most important goal for NASA. For example, NASA has done many studies by “Mars curiosity rover” and “Mars opportunity rover”.
For this purpose, scientists use an approach that includes 19 or 20 abiotic factors, with an emphasis of availability of liquid water, presence of nutrients, temperature, sources of energy and protection from cosmic radiation.



                      Curiosity Rover
                    Credit: Wikimedia

Some liquid water may flow on Mars surface, this can happen only under very specific conditions. Due to the atmospheric pressure of Mars water evaporates or freezes quickly. Therefore, it is very hard to find liquid water on Mars.

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                          Water Flowing on Present-day Mars
                                                 Credit: NASA

As we know existence of elements including: carbon, nitrogen, oxygen, hydrogen, phosphorus and sulfur are necessary for life. Many. Studies have shown that these elements are present in surface of Mars in some rocks. In turn , this can lead to an increase in possibility of life.

Another parameter that contributes to the possibility of life Mars is energy needed for metabolism. This can either be met by solar energy or geochemical energy.

Temperature also plays an important role in possibility of life. Because of loss of atmosphere in Mars, temperature has decreased significantly during the time.

Finally, because there is no global magnetic field in Mars to protect the planet from the life-threatening cosmic radiation, existence of life may not be probable.

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                                      Wind and radiation on Mars
                                                     Credit: NASA

To sum up, because there is lack of factors that are essential for existence of life in Mars, the idea of existence of life in Mars has a long way to go. However, with advancements in technology, we can hope to discover more evidence needed for life in Mars.

Kamyar Kazemiashtiani